Hagler's career began in the 50's when he designed using the trademark Stanley Hagler. He designed for Wallis Simpson, the Duchess of Windsor. Around 1983 he moved to Florida from New York taking his apprentice Mark Mercy, who had joined him a few years earlier. They were later joined by Ian St. Gielar. The Stanley Hagler trademark had evolved in 1979 to include N.Y.C. (points after the initials) and was used until Hagler's death in 1996.
After his death, Mark Mercy and Ian St. Gieler each went their separate ways. Mark Mercy retains the rights to the Stanley Hagler trademark that includes N.Y.C.
Ian St. Gieler continued to design in the Hagler style using the signage Stanley Hagler NYC (no periods) and also Ian St. Gieler on a separate tag. This appears on most of his pieces. Both continued to use materials from Hagler's original stock.